Using two NICs to increase bandwidth on the same route?

[Bill Davidsen]

Michael W Cocke wrote:
> On Sat, 14 Jul 2007 20:24:29 -0700, you wrote:
> 
>>> Michael W Cocke wrote:
>>>> There used to be a way to run two modems as one logical channel to
>>>> boost the attainable bandwidth - is there a way to do that with NICs?
>>>> What's it called (so I can google it)?  I have fiber needs with a
>>>> 10-base-2 budget.  8-(>
>> What are you connected to that is at least half as wide as your NIC?
>>
>> -- 
>> Knute Johnson
>> Molon Labe...
> 
> I rsync two 3.2 Tb (terabyte) servers every 12 hours.  I'd like to do
> it more often, but right now the bottleneck is holding me.  In an
> ideal world I'd put a fiber channel between the two servers, but not
> in the budget (this is my home system).
> 
Why do you need all that bandwidth? You only need to push over the 
changes, not the whole 3.2TB. Unless you are beating the storage to 
death with updates it's a non-issue. Without much tuning you should be 
able to push 50MB/s out a cheap Gbit NIC, is this not enough? Are you 
sure bandwidth is the issue and not handling the metadata?

In any case you can just have several NICs, put static routes on the 
NICs, use jumbo packets, tune your TCP stack for large window sizes, 
boost the memory available to your stack, all standard tuning methods.

I haven't done bonding in a long time, IIRC you are creating a dummy IP 
address which is then routed over two existing "real" addresses, and you 
do it on both ends of the bonded route. In your case, having several 
NICs, with the same IP on each, and static routing on each NIC may do 
what you want.

Note that this will probably mean lots of scripts to set it up, I don't 
believe the graphical network setup will handle this. And if you run a 
dedicated cable from one to the other on a 2nd NIC, you want P-t-P 
configured on the NIC, for performance.

-- 
Bill Davidsen <davidsen at tmr.com>
   "We have more to fear from the bungling of the incompetent than from
the machinations of the wicked."  - from Slashdot